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Abstract:
A [111]-oriented Pt field emitter tip is used to study bistability and oscillations of CO oxidation by field electron microscopy (FEM) under low-pressure conditions (pO2 = 4 × 10−4 Torr, pCO = 8 × 10−8 to 4 × 10−5 Torr) in the temperature range 240 to 450 K. A kinetic phase diagram can be established, obtained on an FEM level with ≍2 nm lateral resolution. Below T ≍ 300 K a region of bistability prevails, and above T ≍ 300 K an oscillatory regime is obtained, thus yielding a cross-shaped phase diagram. These phenomena are surface plane specific and visible at the {011} planes of Pt and their surroundings.
